Electronic sequence space discharge tube network



OC- 9, 1951 B. F. HOLMS ErAL 2,570,448

ELECTRONIC SEQUENCE SPACE DISCHARGE TUBE NETWORK Original Filed Deo. lO,1947 6 Sheets-Sheet l Odi' 9, 1951 B. F. HOLMES ET Ax. 2,570,448

ELECTRONIC SEQUENCE SPACE DISCHARGE TUBE NETWORK Original Filed Dec. l0,1947 6 Sheets-Sheet 2 Oct 9, 1951 B. F. HOLMES ETAL 2,570,448

ELECTRONIC SEQUENCE SPACE DISCHARGE TUBE NETWORK Original Filed Deo. lO,1947 6 Sheets-Sheet 3 wwff--f- @WM/Em A TTORNE Y Oct. 9, 1951 B. F.HOLMES ET A1. 2,570,448

ELECTRONIC SEQUENCE SPACE DISCHARGE TUBE NETWORK Original Filed Dec. lO,1947 6 Sheets-Sheet 4 Oct' 9, 1951 B. F. HOLMES ET AL 2,570,448

ELECTRONIC SEQUENCE SPACE DISCHARGE TUBE NETWORK Original Filed DGO. l0,1947 6 Sheets-Sheet 5 @ww/@mw A TI'ORNEY Oct. 9, 1951 B. F. HOLMES ETAl. 2,570,448

ELECTRONIC SEQUENCE SPACE DISCHARGE TUBE NETWORK 6 Sheets-Sheet 6Original Filed De ,and m success/bn ATTOPNE Y Patented ct. 9, 1951ELECTRONIC SEQUENCE SPACE DISCHARGE TUBE NETWORK Burton F. Holmes andHerbert Harry Heindel, Toledo, Ohio, sssigrrors to SohrrltrDio Casting'Company, Toledo, Ohio, aicorporaton'of Ohio Original applicationDecember 1Q, 19,47, SerialiNo 790,838. Dividedk and this* applicationQctvober 28, 1949, Serial No."1'24,153

s Claims.v (C1. 17e- 320) This invention relates to an electronic sequence operating network involving. space dis,-v

charge tubes for controlling circuits and is 'a division of ourcopending application, Serial No. 790,838, led December l0, 1947, nowPatent No. 2,532,256, issued November 28, 1950.y

The object of the present invention is to provide a novel networkarrangement in the' s equence operation of discharge tubes which hasbeen found very' enicient in operation and par,- ticularlyuseful inconnection with the operation of solenoids for controlling die castingmachine operations' as set forth in our copending application.

An object of the present invention is to provide a network of thecharacter described in which the sequence discharge of the tubes iscontrolled by a special arrangement and interconnection of circuits` forthe maintenance vand removal of grid biasl supply including the re,-Ysetting of the cycle of operations after one complete cycle has beenaccomplished.

More specifically, an object of the invention isk to provide anespecially satisfactory operating bias control and removal thereof forthe Space discharge tubes of the series in an arrangement we have foundsubstantially fool-proof in action, our bias supply circuits involvingin the main three bias circuits for certain of the tubes, namely, a mainbias supply7 circuit for normally supplying a negative bias/t all of thetubes of the series to prevent firing of any of the tubes in normalinoperative position; an auxiliary bias supply circuit for certain ofsaid tubes adapted to temporarily supply bias to such tubes during aportion of the cycle of operation and a third additional bias supplycircuit for certain of said tubes during another period of the cycle ofop# eration, it being an object of our invention to provide a singlesource of bias supply for each of said alternative circuits.

Further objects and advantages are within the scope of this invention,such as relate to the arrangement, operation and function of the re'-lated elements and circuits of the system, to various details ofconstruction and to combina,- tions of parts, elements per se, and toeconomies of manufacture and numerous other features, as Will beapparent from a consideration of the specification and drawings of aform of the invention, which may be preferred, in which:

Figure I is an electrical diagram illustrating the circuits embodyingour invention;

Figure II is a schematic diagram of` the bias supply circuits andcontrols to tubes I, 2l, 3 and 4 ausielso tho outuut oorrtrollssi relaysiu soriwith russo tubos tris, Circuits bsi'us in. the sauro oondiii'orias 'suor/ii iu Figure 'reifer tuerrrsohirrc boing rsoriy' for'orisrstiorr; "Figure VIrrr isv agissons .showing tris truss olf 11,11,@i3d symwls, We@ ,1.1.1, Figui@ 1I 31S, Wen

su'oo'osdirrs figures:

rieure r11 is a sohsrriatis diarrrriri` similar to Figure 11 butwithths. tirouits' and Controls in tos souri.' ,io'rr thor' essuirisfstthstirus of tirs firing of'tubs, l; .Fisuro IV is o schematic diagramsimilarto Fisurs' 1,1 butwiti' tirs" sirsuitsfsr'id soutruls iu" tho'Condition. trios! assume et trio time' oir tris'ririrrs'or tubs .Zr l

'Figure V is Aa schematic diagram similar to Figure Il but withthe-'circuits and controls in 11? condition they assume Lasthetime'ofthel gringo-f tuners.; l

Figure V1 isv s sohsrristis diusrsrri similar to Figure II butwith thecircuitsand controls in tho Condition they assumo et tirs' time" of thfiring of ytube 4, and" immediately thereafter.

lIrl tho` orubosiirrierit of our irirsrition illustrated in theaccompanying drawings, we yhave sriowu su slootrissi srstfsrrrssrt'isuirrlr adapted `for uso .ilu operating s uis oastiris maohiusirlu'strated in 4our" copending applicationy and in? cluding a" sourceof electrical current supply and the electronic sequence' ,timingnetworkadapted to be operated fromwvsaidcurrent"supply which includes aplurality of space discharge tubes l?, ,2; 3 sus 4;, 'tho bissirisfdisojurss: rrid' rsbiss* infr of which ers Prourrlrsorrtrollsd'in"a ut;-sirsu msuusr .toi oserais srrrrssst 'relaysy soisnoids, andinterconnected electrical v'circuits and ,apparatus ror ooritrolliugtris uotiou of crtin machine `moving elements, the Yelectrical networkiritoroorrusstsd with 'tuddsprids'ut iu sort upon a movement of a partofthe machineit'- sem Referring toA Figure 1I of tris drawings., it willro understood' that 'tirs ris-uri, ooo'rstld switch G40 is connected tovtheA power'lin'e through a temporarily locking 'inil Switch mechanismthrough los@ .490: tol .soil A0? whioh orisrsizss coil 4.02 sus''oorrssuusrruymsos cantas-ts' softhst the die casting 'machine clos s.Eollloiwing this operation, `our ,ristrrork Psrrtioui'arly adapted uponthe, rngy ,Qf the'. thyir'ifrcii 13111095 zl ansi 4: to* oporstsf trisrritulfirriootiorr" irl tir-o stages', rossi' tlisbias ou ,sortais oftbs tubos. sus open the ies and y,complete the resetting oflthe `mi@ toYmina; position; 'In oouusotiorr wir@ r,slrstrissu .Circuits uisclosed,we have a 220 volt input circuit supplied through leads 90, 9| and 92and a main transformer 465. From this main transformer 465 we provide a110 volt circuit to the primary winding of a second transformer 415, thesecondaries of which supply current to the filaments of tubes I, 2, 3and 4 at 6.3 volts and another circuit for a heat control including a 6volt circuit for a rectier tube and a high voltage for the plate of thesame to supply a negative direct current for the grid bias circuits forthe thyratron space discharge tubes 2, 3 and 4. Another transformer 482has a primary winding which is also energized from transformer 465 andhas a 24 volt secondary winding adapted to supply current to a 24 voltcircuit arrangement of leads and relays for ef fecting supply of currentfor electrical means for actuating the apparatus with which thisinvention is concerned.

The plate circuits for the tubes include the terminal 468 as a commongrounded cathode circuit rrom transformer 465. `On the other side fromsaid transformer, the plate circuit includes the fuse 480, lead 500, tonormally open point 50| on relay 406 when point is closed in theautomatic position of the apparatus. From point 50| We provide lead 502to normally open point 503 on relay 430 also closed in the automaticposition after time delay for the tube warm up has taken place(hereinafter described). Lead 505 from point 503 connects With terminal506, all tube plate circuits connect from terminal wire 506. Thus, fortube we have a lead 501 connected to lead 506', resistor 508 to limitthe current ow, lead 509, t coil 5|0, lead 5|| to the plate of tube I.The cathode circuit of tube I is grounded as indicated by a circuit |3.We also have a condenser 5|2 connected across coil 5| 0 to supplycurrent to coil on the negative onehalf cycle and prevent chattering.

The other tubes 2, 3 and 4 are similarly connected.

Thus for tube 2 lead 5I4 is connected to the lead 506 common to all oftubes I, 2, 3 and 4 as indicated supra. Lead 5|4 connects throughresistor 5I5, lead 5|6, to coil 596, hence by lead 5|1 to the plate oftube 2. A condenser 5| 9 is connected across leads 5I5 and 5I1, asshown.

For connecting tube 3, we provide a, lead 520 passing through theresistor 52| to lead 522, which connects with coil 600 having lead 524connected to the plate of tube 3. A condenser 525 is connected acrossleads 522 and 524. The cathode circuit of tube 3 is grounded asindicated by circuit 526.

For tube 4 we also provide a lead 530 connected with a common connectinglead 506', limiting resistor 53|, lead 532, coil 4|2, lead |3I, to theplate of tube 4. We also provide a condenser 535 across leads 532 and|3| as in the case of the other three tubes. The cathode of tube 4 isalso grounded by circuit 531 as indicated.

Bias circuits `550 for the 6.3 volts for the filaments of the thyratrontubes l, 2, 3 and 4. Another secondary output circuit of 5 volts isindicated 55| for the rectifier tube 553.

The third center tapped winding 554 of the transformer 415 is forsupplying voltage to two circuits, one the plates of a rectier tube 553and the other for the main thyratron tube bias circuit. We have groundedthe filament (cathode) of rectifier tube 553 as shown. At the center tapof the secondary 554 we have a lead 555 to resistor 556, lead 551combined choke and relay coil 499. From lead 551 we also have a lead 558to condenser 559, the other side of which is grounded as shown.

From coil 499 we have lead 560 to the cathode of voltage regulator tube56|, the plate of which is grounded as indicated. Across tube 56| is aresistor 562 connected by lead 563 to lead 560 to said tube 56|, theother side of resistor 562 being grounded.

Our connections for these tubes also forms a time delay for the warmingup of tubes I, 2, 3 and 4, since relay 499, when energized, closespoints 499', there being a time delay on the make of said points 499with a, well-known type of switch which has a quick break.

Moreover, this relay 499 provides a safety arrangement since failure ofany part of the bias supply will cause 499' to open, dropping out relay430 which disconnects the plate circuits of the tubes 2, 3 and 4. Thisalso drops out the 24 volt control circuit to the automatic operation.

Connections for vthe bias supply voltage for tubes 1, 2, 3 and 4 Theabove circuits and the tubes 553 and 56| provide means to produce thebias voltage for the main thyratron tubes 2, 3 and 4. We will nowdescribe its connections to these tubes. Thus we have a lead 565 joinedto lead 563 as shown. Lead 565 is the main bias supply line for all fourtubes. This main lead 565 connects with three points (normally closed)on relay 566; namely, points 561, 568 and 569, lead 565 also beingconnected with points 510, 51|, 512 and 513 of relay 600 controlled bytube 3.

For tube bias is normally supplied from lead 565 to point 561, lead 511,resistor 518 and lead 519 to the grid of tube I.

For tube 2, the main bias is from point 568, lead 580, resistor 58|,lead `562, to the grid of tube 2. This main bias lead 565 also has aconnection for an auxiliary circuit for tube 2 by lead 515 to a contact516 of relay 5||l controlled by tube For tube 3, the main bias includeslead 588 from point 569, to resistor 584, lead 585, to the grid of tube3. Tube 3 also has an auxiliary bias circuit, since Iwe provide, as moreclearly shown in Figure II, a lead from a bias line 565 to point 512 ofthe relay 600 as shown. We also provide a lead 512 from point 512 topoint 595 of relay 596 of tube 2. Then we also provide a lead 595connecting with lead 583 to the grid of tube 3. Hence, the auxiliarybias for tube 3 is so connected as to have in series therewith a switchcontrolled by the relay for tube 2.

For tube 4, the bias includes a lead 581 from point 513 to resistor 588,lead 589, to the grid of tube 4. As the necessary part of the operation,as will hereinafter appear more fully, we also provide additionaltemporary bias circuits for tubes and 2. This additional bias for tubesand 2 includes a circuit from switch point 510 of relay 600 by way oflead 510 which connects with relay point 51| bylead 51|' which connectswith lead 580 tothe grid of tube 2v.

Sequential firing of tubes We have provided means for causing tubes I,2., 3 and 4 to re in a desired sequence. for

proper machine. operation one after the other,

and moreover, any.` subsequent tube in the series cannot rire until thepreceding tube has tired.- The." circuits and means for.accomplishingjthis willfnow be described. Thus, when relaycoil 566.

is,.'ener'gized this openspoints 56.1, 568K-an'd 569, removing the mainbias` from tubes I, 2 and 3. However bias for tubey 2 is now beingsupplied through the'temporary auxiliary circuit constitilting a secondsupply circuit for tube 2 just described and including point 516, lead590, lead 580, resistor 56|, lead 582vv togrid of tubefZ. When tube Ires (at the endof its time delay, to be described) relay 5I6, throughlead 5II, isdthen energized and normally closed point 516- now opens,removing this auxiliary bias from tube 2.

Also the ring of tube I and energizing of coil 5|0 closes the normallyopen point 592 thereby applying 24 Volts to the power relay I2 'byleads631 to apply a delayed shot of metal into the mold of the die castingmachine.

Firing of. tube 2 Firing of tubev 3 Removing bias from -tube 3allowstube, 3 to fire at the end of its time delay energizing the coilof relay 666, closing normally open points 51,0 and 51I, therebyreapplying the third or temporary additional bias to tubes I and 2, thusresetting these tubes and their associated plate circuit relays.

Moreover, normally closed points 51,2 and 513 are opened and since 512is opened, thisprevents reapplying bias to tube 3 by tube 2 at thispoint of the` cycle.

Firing of tube 4 The opening of 513yremoves bias frommtube 4. When tube4 fires at the end of its time delay, the relay 4I2 is energized,openingmnormally closed point H3 which breaks the holding ,circuitfurthe die operating mechanism.

Interconnected. circuits from tube controls to machine part operatedmicroswitch. to-tube3 The. bias control of the tube 3 is interlcckedwith a microswitch 602 which switch in` turn. is actuated by the. rackon the machine, which .rack is operated by a hydraulic system.y Closing,of point 602 closes relay 605 byleadsffrom contact 49,6,ofrelay 436A andleads 408, -'Illlland 606. An-l otherlead ,661 connects. from. lead60.6I to va .point 60,8,"(normally open) of relay 4 I 2.r

011th@ other Side 0f, 10.11,I 60.5. e lead, 5l". We:

for operating the. check valve nects with normally.A open'. side.-` ofimcrosvvitx'shr 602, referred to supra and lead. 6.II.; leadsgn. andi425,normally. open pointi.42,6r, on relay 430.

Whencoil 6;5-;is. energized, coilof relay. 566; isv4 also energized.Relay.y 605 has. three normally'. open points 612; points. 6I3fI and6I4.. Theconnection from relay,l S05/.to yrelay 56.6;.includes point; 6=I2,= lead. 615, relay... coil 566. From the other. side of relay. 565,lead 616 connectsto lead.,` 4.19,; point 4 I Bofrelay 4.02, theotherside ofthe switch. 4I8 nasa-lead 4.I.1 extending. to terminal M6;henceibylead IiIIL to` safetyl point 6.I9r.of push; button switch 646.which also. connects. to-leada 6-20iandconnection 62I, lead 623, whichconf nectsto `lead 6Il6acompletingthe circuit for enf ergizing coilSI15-and hencecoil 566; Thus, when;` point 6ll2opens,` due to the actionof thev machine. part-with theedies starting. to open, from'fthef`foregoing circuitsritwill be `seen that coil 6.05v and hence coil.566;:are. de.energized, all three, points 561, 5,68 .and -569 of relay.566 areclosed,v thus reapp-lying the main original bias to tube 3 aswell as to tubes` I and 2.

After relay 566 vh-asbeen deenerg-ized and the mai-nv bias, restored,Vto tubes I ancl- 2 the additional bias'ior-LtubesfI and-2 abovedescribed. hasfbeen broken by the biasing of tube 3. This occurs sinceIthe main bi-as'is restored-immediatelytc tubes I andf-2 whereas theadditional bias circuitis not broken-until tube 3 becomes biased andrelay 600- subsequently operates to break points 516 andv 51|Y ofgsaidadditional bias circuit.

Time delay circuits ,for tubes 1, Z, 3 and 4 For eachof tubes I, 2, 3and 4 we have a time delay network for the bias circuits thereof whichincludes lead 511 (bias supply lead for tube rek--r sister 518) leadA519 for example, to grid of tube` I.l Before normallyl closed point 561opens, there isla circuit` through" resistor 518, lead 519, whichalsoueharges condenser 660 which until the bias is', removed, supplies avoltage to grid I. Howf evenwhen VSwitchpoint 561 is opened, condenser666 is. discharged through adjustable potentiometer 66I (which, may bevariablyset by the opcrater) andk current limitingY resistor 662 toground 5I3 asV shown. The other side of the bias circuit is grounded asshown in the drawing and described supra. Thus, the setting of the ad-,fjustrnent aon potentiometer 66| determines the time for dischargeofmcondenser 668 which when it reaches critical grid Vvoltage of tube Iallows thetube to re. Resistor 662 limits the current for a very lowsetting of the potentiometer 56|. Resistor 518 has two purposes, one toprevent the main bias supply from being shorted in case condenser 660fails. Also it provides a buiter action toprevent burning of point 561,due to sudden inrush of current to condenser 660. A similar time delaynetwork consisting of a similar condenser 660 and potentiometer 66| forthe dise charge of the bias isprovided for each of the other tubes 2, 3and 4 as shown in the drawing.

Operation-.Une `complete cycle The .system is started in operation bytheoperator closing the. quick returnclose button 64,0 throughrelay 402,relay .406 and correlated cir-v cuits, andcontrols from the relay 430connected atrofisaA and conditions at this point are shown in diagramFigure II.

The microswitch at point 602 is operated by a machine part to therebymove the microswitch to final closed position and effect an energizationof relay 605. This closes switch point 6I2 and relay 566 is energized,opening point 561 which is in the main bias circuit for tube I-thisbeing the main bias circuit for tube I as well as for the other tubes asdescribed above. Opening the tube I bias, permits tube I to fire throughits plate circuit at the end of its time delay, thereby energizing relayI0, closing switch point 592 as stated supra. The circuits at this pointare illustrated in Figure III. This, through the various circuits shown,energizes relay I2 which in turn supplies power to the pilot valve forthe main air cylinder 5I, permitting a delayed shot of metal to beinjected into the die as the first part of the two-stage metalinjection.

Temporary auxiliary circuit for biasing tubes 2 and 3 It will be notedthat while the main bias supply circuit to the tubes controlled by relay566 and points 561, 568 `and 569 has been broken, tubes 2 and 3 aretemporarily biased by the auxiliary circuits described above. Theseauxiliary circuits for tubes 2 and 3 have been temporarily energizedsimultaneously with the main bias described above and the auxiliary biascircuits for these two tubes are illustrated in the diagram of FigureII.

Firing of tube 2 By the firing of tube I, just described, the auxiliarybias for tube 2 is opened because switch point 516 which is in the biascircuit for tube 2, has now been opened by relay 5I0. Removing thisauxiliary tube 2 bias causes the discharge of its circuit at the end ofits time delay since the main bias supply was previously removed,energizes relay 596. The circuits as now operating are illustrated inFigure IV. Thus, when point 591 is closed, current is supplied from thetransformer 482 to relay I I circuits and switches for rapid metalinjection. However, since the time delay in the f1ring of tube 2 afterboth bias circuits have been removed depends on setting of the variablepotentiometer 66| for tube 2, by adjustment thereof to its low position,tube 2 may fire substantially immediately after tube I fires so that inthe overall operation of the network sequential firing system disclosed,tubes I and 2 in such case lire without any appreciable difference intime but act as one tube.

Firing of tube 3 The firing of tube 2 energizes coil 596 which breaksthe auxiliary bias supply for the grid circuit of tube 3. Since the mainbias supply was previously removed this now removes all bias from tube 3and causes it to fire after its time delay-illustrated in Figure V.

Firing of tube 3 acts to reset bias of tubes 1 and 2 Next in the cycleof operations, we provide means through the firing of tube 3 to resetthe bias by the additional or a third temporary circuit for tubes I and2, described supra. However, ring of tube 3 energizes relay 600 which islin the plate circuit of tube 3 as shown, so that energization thereofcloses switch point 510 and 51| which are in the additional biascircuits for tubes I and 2, as described above and shown in Figures Iand V. By closing these switch points 510 and 51|, tubes I and 2 arerebiased. It is understood that when the proper bias is applied to tubesI and 2, discharge thereof through the plate circuit ceases.

Precention of rebiasing of tube 3 To prevent improper rebiasing of tube3, we have also provided another switch point 512 for relay 600 so thatwhen relay 600 is energized, as just stated, this switch point 512 openswith the result that re-establishing bias of tubes I and 2 will not alsore-establish bias of tube 3.

From the foregoing it will be understood that when bais isre-established to tubes I and 2 these tubes cease firing and coils IIand I2 are deenergized, permitting solenoid operated pilot valves 5I and6I to be returned to normal position.

Firing of tube 4 and resetting circuits to initial position Firing oftube 4 is for the purpose of accomplishing the last step in the machineoperation in our system; namely, re-opening the dies which in turn, bythe machine controlled switch 602, causes return of circuits to initialposition with the main bias on tubes I, 2, 3 and 4. This is illustratedin Figure VI. Referring back to tube 3 it will be noted that when itfires, it has Opened switch point 513 on relay 600 which in turn removesthe bias from tube 4 after its time delay through its potentiometercircuit 6I I-4. VWhen the bias on tube 4 is removed, then the tubedischarges, energizing coil 4I2, opening point 4|3 on relay 4I2, therebybreaking the holding circuit for relay 402 which drops out relay 402.This effects an opening of the dies and consequently opens microswitch602 which deenergizes relay coil 605 and consequently coil 566. Thisallows points 561, 568 and 569 in the main bias circuit for the tubes I,2 and 3 to be re-established, thereby resetting these in initialposition. Rebiasing tube 3 in this manner thereupon permits its relaycoil 600 to operate, breaking points 51I and 510 thereby disconnectingthe additional bias circuits which were temporarily established fortubes I and 2. It will be also noted that this operation of relay coil600 also closes point 513 which establishes the main bias supply to tube4. The entire electrical apparatus is now in initial position. Thesystem will not recycle until the operator restarts the action bypressing the manual close button 640 as heretofore described.

In referring to the bias supply circuits for the several tubes, we havereferred in Figure IIa and in the description thereof to the main bias,an auxiliary bias and an additional bias. However, it is to beunderstood that the various circuits-some leads of which are common tothe different circuits--for supplying bias at the proper time t0 thedifferent tubes, according to the drawings and description may beproperly termed additional or supplemental with respect one to other ofthe bias circuits.

It is apparent that, within the scope of the invention, modificationsand different arrangements may be made other than is herein disclosed,and the present disclosure is illustrative merely, the inventioncomprehending all variations thereof.

What we claim is:

l. In an electrical system for causing mechanical operations, saidsystem adapted to be connected to a source of electric current, anelectronic sequence timing network adapted to be energized vfrom said`source of current; said network including a plurality of spacedischarge tubes connected in said network; each -of said tubes havingcathode, plate and control 4grid elements; a iplateecathode 'circuit foreach of said tubes; and fa variable Itime constant network forcontrolling 'the vsequential discharge `oi said tubes, -saidnetworkincluding a capacitance and resistance connected to the grid4element of 4each of said tubes; a source of bias supply; la mainnormally closed bias circuit; switching means therefor for connectingsaid main bias supply to the control Vgrid Velements of each yof saidtubes to prevent firing thereof; auxiliary bias Vcircuits for thecontrol grid elements of certain'of Vsaid tubes upon opening of the mainbias circuit to said tubes; means operable to open the switch of themain bias supfply circuit to aplur'a'lity of :said tubes, said means"causing ldissipation of the 'capacitance from the `g-rid `'circuit 'ofvone of lsaid `tubes through its re- Tsistance causing delayed`discharge of said one tube only through its plate-cathode circuit;'switching means connecting said auxiliary bias to certain of the otherof 'said tubes when said main bias switch is opened; means operated bythe discharge of said first-mentioned tube to'open fsaid auxiliary biassuppl'y circuit to lthe control grid 'of a second tube to permit'delayed discharge "thereof; means controlled by the discharge of I'saidlsecond tube for *opening the auxiliary bias 'circuit vfor a third tubeto *cause discharge there- Cof; additional bias circuits for 'the iirsttwo mentioned tubes; Yswi'tcl'ii'n'g means controlled by said -thirdtube discharge circuit for connecting said additional bias Ycircuits forthe rst two tubes to the bias supply to rebias 'said tubes; switchingfineans for breaking 'thebias supply to a fourth tube; and means underthe control "of 'said-last'- mentioned tube 'to Yclose 'the'first-'mentioned main bias supply circuit to each of said lplurality oftubesin said system.

2. In an electrical systernior causing mechanical operations, saidsystem adapted to be connected to a source of electric current, anelectronic sequence timing network adapted to be "ener- 'gized from saidsource of current; said network 'including a plurality of spacedischarge tubes 'connected in said network; each of said tubes havingcathod-e, plate and 'control grid elements; a plate-cathode Vcircuit forleach of said tubes; and a variable time constant network forcontrolling the sequential 'discharge of said tubes, said networkincluding a capacitance and resistance connected to the grid element ofeach of -4said tubes; a source of bias supply; a main normally closedbias circuit; switching means therefor for connecting said main biassupply to the control grid elements of each of said tubes to preventfiring thereof; auxiliary bias circuits for the 'control grid elementsof certain of said tubes `upon opening nf the main bias 'circuit to saidtubes; mea-ns operable to open the switch of the main bias supplycircuit 'to a'plurality of said tubes, said means causing .dissipationof the capacitance from the grid circuit of one of `said -tubes throughits resistance causing delayed discharge of said one tube only throughits plate- 'cathodecircu-it; switching means connecting 'said auxiliarybias to certain other of 'said Vtubes when said main bias switch isopened; means operated by the discharge of said first-mentioned tube toopen said auxiliary bias supply circuit to the control grid of a tube topermit delayed discharge thereof; additional bias connections forcertain of said tubes; switching means controlled by a previouslymentioned tube discharge circuit for connecting said additional biascircuits to the bias supply to rebias certain of said tubes; switchingmeans for breaking the bias supply to another tube; and means under thecontrol of said last- `mentioned tube to close the inst-mentioned mainbias supply circuit to each of said plurality of tubes in said system.

3. yIn -an electrical system for causing mechanical operations, saidsystem adapted to be connected to a source of electric current, anelec-.- tronic sequence timingl network adapted to be energized fromsaid source of current; said network including a plurality of spacedischarge tubes; each of said tubes having cathode, plate and controllgrid elements; a plate-cathode circuit for each of said tubes; rand aVariable time constant network for controlling the sequential dischargeof said tubes, said network including a capacitance andresistancefconnected to the grid element of each of -said tubes; asource of .bias supply; a main normal-ly closed bias circuit; `switchingmeans therefor for connecting said main bias supply to the control gridelements of each of said tubes to prevent firing thereof; auxiliary biasconnections for the control grid-of certain of said tubes upon openingof the main bias circuit to said tubes; means 4operable to open theswitch of the main bias supply circuit -to a plurality of said tubes,said means Vcausing dissipation of the capacitance from the grid circuitof one of said tubes through its resistance causing delayed discharge ofsaid one tube only through its plate-cathode circuit; switching meansconnecting said auxiliary bias to certain of the other of :said `tubeswhen said main bias -switch is opened; `rmeans operated by the dischargeof -said first-mentioned tube to open said auxiliary bias supply circuitto the control grid of a second tube-to permit delayed dischargethereof; vmeans controlled `by the discharge of 'said Vsecond `tube foropening the auxiliary bias circuit for a third tube to cause delayeddischarge thereof; the auxiliary bias circuit for said third tube beingin series with the vswitch points of the `switch means operated 'by thedischarge of each of said 'second and `said third tubes to preventreapplication vof bias to said lthird tube through said auxiliarycircuit; ,additional -bias circuits for the first two Vmentioned tubes;switching means controlled -by said third tube d-ischarge'circuit forconnecting said xadditional bias circuits for the first two tubes to thebias supply to rebias said tubes; switching means 'for breaking theybias supply to a yfourth tube; `and means under the lcontrol of saidlast-mentioned tube to yclose ythe -rst-inentioned main bias supplyvcircuit tofeach of said plurality of tubes in said system.

` 4. In an Aelectrical system `for causing v'mechanical 'o'perationssaid system adapted to be connected to a source Lof electr-ic current,an velectronic sequence timing network adapted to be y'energized fromsaid source of current; a tying-'in relay; `circuits and switches fromsaid source of current supply to said relay; lcircuits controlled by'said relay to connect said source of supply to 'said network; `saidnetwork including a plurality of 'space discharge tubes connected insaid network; each o'f Isaid tubes "having cathode, plate and controlgrid elements; a plate-cathode circuit for each of said tubes; and avariable time constant network for controlling the sequential dischargeof said tubes, said network including a capacitance and resistanceconnected to the grid element of each of said tubes; a source of biassupply; a main normally closed bias circuit; switching means thereforfor connecting said main bias supply to the control grid elements ofeach of said tubes to prevent ring thereof; auxiliary bias circuits forthe control grid elements of certain of said tubes upon opening of themain bias circuit to said tubes; means operable to open the switch ofthe main bias supply circuit to a plurality of said tubes, said meanscausing dissipation of the capacitance from the grid circuit of one ofsaid tubes through its resistance causing delayed discharge of said onetube only through its plate-cathode circuit; switching means connectingsaid auxiliary bias to certain other of said tubes when said main biasswitch is opened; means operated by the discharge of saidfirst-mentioned tube to open said auxiliary bias supply circuit to thecontrol grid of a tube to permit delayed discharge thereof; meanscontrolled by the discharge of said tube for opening the auxiliary biascircuit for another tube to cause delayed discharge thereof; additionalbias connections for certain of said tubes; switching means controlledby a previously mentioned tube discharge circuit for connecting saidadditional bias circuits to the bias supply to rebias certain of saidtubes; switching means for breaking the bias supply to another tube; andmeans under the control of said lastmentioned tube to close thefirst-mentioned main bias supply circuit to each of said plurality oftubes in said system.

5. In an electrical system for causing mechanical operations, saidsystem adapted to be connected to a source of electric current, anelectronic sequence timing network adapted to be energized from saidsource of current; a tying-in relay; circuits and switches from saidsource of current supply to said relay; circuits controlled by saidrelay to connect said source of supply to said network; said networkincluding a plurality of space discharge tubes connected in saidnetwork; each of said tubes having cathode, plate and control gridelements; a plate-cathode circuit for each of said tubes; and a variabletime constant network for controlling the sequential discharge of saidtubes, said network including a capacitance and resistance connected tothe grid element of each of said tubes; a source of bias supply; a mainnormally closed bias circuit; switching means therefor for connectingsaid main bias supply to the control grid elements of each of said tubesto prevent firing thereof; auxiliary bias circuits for the control gridelements of certain of said tubes upon opening of the main bias circuitto said tubes; means operable to open the switch of the main bias supplycircuit to a plurality of said tubes, said means causing dissipation ofthe capacitance from the grid circuit of one of said tubes through itsresistance causing delayed discharge of said one tube only through itsplate-cathode circuit; switching means connecting said auxiliary bias tocertain of the other of said tubes when said main bias switch is opened;means operated by the discharge of said rst-mentioned tube to open saidauxiliary bias supply circuit to the control grid of a second tube topermit delayed discharge thereof; means controlled by the discharge ofsaid second tube for opening the auxiliary bias circuit for a third tubeto cause delayed discharge thereof; additional bias circuits for the rsttwo mentioned tubes; switching means controlled by said third tubedischarge circuit for connecting said additional bias circuits for thefirst two tubes to the bias supply to rebias said tubes; switching meansfor breaking the bias supply to a fourth tube; and means under thecontrol of said lastmentioned tube for simultaneously directlyconnecting the main bias supply to the iirst three tubes; meanscontrolled by said last-mentioned biasing of the third tube forthereafter simultaneously disconnecting said additional bias supply tothe rst and second tubes.

6. In an electrical system for causing mechanical operations, saidsystem adapted to be connected to a source of electric current, anelectronic sequence timing network adapted to be energized from saidsource of current; said network including a plurality of space dischargetubes connected for sequential operation in said network; each of saidtubes having cathode, plate and control grid elements; a plate-cathodecircuit for each of said tubes; and a variable time constant network forcontrolling the sequential discharge of said tubes, said networkincluding a capacitance and resistance connected to the grid element oieach of said tubes; a source of bias supply; a main normally closed biascircuit; switching means for connecting said main bias supply to thecontrol grid elements of each of said tubes to prevent firing thereof;means operable to open the switch of the main bias supply circuit to aplurality of said tubes, said means causing dissipation of thecapacitance from the grid circuit thereof through its resistance causingdelayed discharge through the plate cathode circuit of one tube only;additional bias circuit means adapted to be connected to a sequentialtube; switching means controlled by said first-mentioned dischargecircuit for opening said last-mentioned additional bias circuit topermit delayed discharge thereof; switching means controlled by saidsequential tube discharge circuit for rebiasing said rst-mentioned tubeand for breaking the bias supply of another tube; and means under thecontrol of said last-mentioned tube to close the first-mentioned mainbias supply circuit to each of said plurality of tubes in said system.

BURTON F. HOLMES. HERBERT HARRY HEINDEL.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,422,020 Kingsmill June 10, 19472,483,620 Burlingame Oct. 4, 1949 2,503,127 Mumma Apr. 4, 1950 FOREIGNPATENTS Number Country Date 504,680 Great Britain Apr. 28, 1939 OTHERREFERENCES Review of Scientific Instruments, Nov. 1939, pages 323 and324.

